1. Field of the Invention
The present invention relates to a roller type linear guide bearing having dust seals and protection covers.
2. Description of the Art
A prior art roller type linear movement guide bearing includes a roller train having a plurality of rollers infinitely circulating while rolling in contact with a raceway surface, a main body supporting a load through the roller train and having side surfaces for guiding the roller train, and end caps for making a U-turn of the roller train at opposite ends of the main body. The roller type linear movement guide bearing is linearly movable in an axial direction along the raceway surface with which the roller train is in contact.
Such a roller type linear movement guide bearing is used by being interposed between a table and a raceway surface of a guide rail or a bed so that the table performs a reciprocating linear movement smoothly and lightly along the raceway surface.
However, in the prior art roller type linear movement guide bearing, the end caps at opposite ends of the bearing are exposed to the outside without any protection covers. Furthermore, since the end caps are synthetic resin molded products in order that the curved paths for enabling the roller train to make a U-turn are easily formed, the mechanical strength of the end caps is low. As a result, a problem is involved in that when the linear movement guide bearing accidentally falls on the floor, or when an article inadvertently strikes the bearing, the linear movement guide bearing can be damaged.
Furthermore, when dust or cuttings intrude into the inside of the linear movement guide bearing, the function of the bearing will be seriously affected. Accordingly, it is necessary to use a dust seal. However, in the prior art, since the dust seal is not built in the roller type linear movement guide bearing, the user himself must procure an outside-fitted seal and attach it suitably. Thus, there is a problem in that the attaching is cumbersome and requires manhours of labor and this in turn makes the use of the roller type linear movement guide bearing itself inconvenient.
FIGS. 6 and 7 show an example of one way of attaching a prior art dust seal. A roller type linear movement guide bearing 1 is mounted within a recess 5 provided in a table 4 such that a roller train 2 is in contact with a raceway surface 3. A slant surface sliding mechanism 6 for applying a preload is interposed between the table 4 and the linear movement guide bearing 1. A dust seal 7 for an axial end of the roller type linear movement guide bearing 1 is attached to a cover 8 of the recess 5 of the table 4 and seals a clearance between the cover 8 and the raceway surface 3. Further, a dust seal 9 for a lateral side of the linear movement guide bearing 1 is attached through a spring 11 within a seal groove 10 formed in a lower surface of the table 4 and seals a clearance between the table 4 and the raceway surface 3.
Furthermore, since the space of the recess 5 of the table 4 partitioned from the outside by the outside-fitted seals 7 and 10 is filled with a large amount of grease surrounding the roller type linear movement bearing 1, the cost of maintenance is high.